Producing lubricating oils by solvent extraction



Jan; 6, 1959 c HOLDER ET AL 2,867,583

PRODUCING LUBRICATING OILS BY SOLVENT EXTRACTION Filed Oct. v. 1953 BExu I. 7 om 0v Al Al hw mm S uzxqamn mm 51 :vn B 0 3535mm mm 5% E zrt mmqamo wit 1v mm mv 2 f a 5 3 f on Q Q/ F. :& f 36 98 N m AI & l =o md 5Em A v N in mzwsmqu V 5N mz u 6%? :r m 55 mozotgE E51 :6 on @2235 25 550Clinton H. Holder Walfer M. Busch Inventors Attorney United StatesPatentO PRODUCING LUBRICATING OILS BY SOLVENT EXTRACTION Clinton H.Holder, Westtield, and Walter M. Basch,

Rumson, N. J., assignors to Esso Research and Engineering Company, acorporation of Delaware Application October 7, 1953, Serial No. 384,744

5 Claims. (Cl. 208327) The present invention is concerned with animproved process for the production of high quality lubricating oils.The invention is more particularly concerned with high qualitylubricating oil blends comprising virgin streams in combination with astream secured from a catalytic cracking operation. In accordance withthe present invention, the lighter or lower boiling constituents of widevirgin distillate fraction are removed and are preferably passed througha catalytic cracking operation. These constituents are replaced bystreams secured from the catalytic cracking operation to produce highviscosity index lubricating oil having other beneficial qualities.

It is well known in the art to produce lubricating oils by variousprocesses comprising distillation operations and the like. One criterionutilized to determine the quality of a lubricating oil is the viscositycharacteristics of the oil. In many operations the temperatures at whicha lubricant is employed vary hundreds of degrees. Thus, it is essentialto provide lubricating oils which have proper viscosities over theentire range of operating temperatures at which they are used. Therelative change in viscosity of an oil as it is heated is generallyreferred to as the viscosity index of the oil. Thus, the viscosity indexof an oil provides information as to the change in viscosity of the oilover the temperature range of 100 F. to 210 F. It is apparent that formany uses it is very desirable to employ lubricating oils having thehighest possible viscosity indices.

In general, three types of hydrocarbons are to be found in thelubricating oil fraction of a crude petroleum, namely parafiinic,aromatic, and naphthenic hydrocarbons. It is known that the paraflinictype hydrocarbons have by far the highest viscosity indices, as forexample, in the range of about 125 to 180. Naphthenic and aromatic typehydrocarbons have materially lower viscosity indices. If these typematerials are rich in ring structures, the viscosity indices are below0. Because of this, paraifinic type crude oils have long been consideredto be the best source of lubricating oil. However, truly parafiiniccrude oils are unusual, and more often, crude oils are of the mixed basetype, containing a combination of paraflinic, naphthenic and aromatictype hydrocarbons, all of which are present in substantial proportions.Examples of such crude oils are Panhandle, Louisiana, Mississippi, EastTexas and Middle East crude oils; 1 f

Many efforts have been made to provide suitable processing methods forproducing high quality, high viscosity index lubricating oils from suchmixed base crude oils. In particular, it has been found that byemploying solvent extraction processes, lubricating oils may be mademore paratfinic by the selective removal of aromatic type compounds.However, the solvents are employed for the removal of the aromatic typecompounds are less selective for removing naphthenic constituents andthe one or two ring non-condensed aromatic constituents. As a result,lubricating oils obtained by solvent extraction processing arecharacterized by containing relatively large proportions of naphtheniccompounds and the one or two ring 2,867,583 Patented Jan; 6, 1959 ICCaromatic compounds having long side chains. These constituents lower thepotential viscosity index of the oil.

When manufacturing lubricating oils of various viscosity grades, it iseconomically attractive to process the corresponding fractions from thecrude in admixture as a wide boiling feed stock. This saves considerabletankage and lines compared to separate processing of individualfractions. While this is an attractive method practically, there havebeen found to be process advantages that arise when processing the wideboiling stock. This occurs in the extraction step in that there is atendency to overextract the light part of the wide boiling stock andunder-extract the heavy portion. This is because of-the tendency of thesolvent to dissolve low molecular weight components in preference tohigh molecular weight components of the same or equivalent molecularstructure.

This over-extraction leads to a low viscosity fraction of very highviscosity index, which fraction is often unstable in engine performance.This also occurs when narrow boiling oils are too severely extracted andis due to the removal of natural oxidation inhibitors. These results aremeasured by the Sligh test and the Conradson carbon value. It is onepurpose of this invention to overcome this inherent disadvantage of widecut extraction. It has been found that if the light virgin fraction isreplaced by a cycle stock, the low viscosity finished lube oil will havemuch better oxidation stability. In this manner, the wide boiling lubestock processing becomes very attractive since the oxidation instabilityof the low viscosity lube is avoided.

In accordance with the present invention, a high quality, high viscosityindex lubricating oil is secured by removing the lower boilingconstituents from a wide cut lubricating oil fraction. These lowboilingvirgin lubricating oil constituents are replaced with crackedhydrocarbon constituents of substantially the same boiling range andviscosity.

The process of the present invention may be .more fully understood byreference to the drawing illustrating one embodiment of the same. 7

Referring specifically to the drawing, a crude oil, as for example, aMiddle Eastcrude, is introduced into distillation zone 1 by means offeed line 2. Temperature and pressure conditions in zone 1 .are adjustedto remove overhead by means of line 3 normally gaseous hydrocarbonconstituents. Hydrocarbon constituents boiling in the motor fuel boilingrange are removed from distillation zone 1 by means of line 4 whileconstituents boiling in the light distillate range, as for example,kerosene, diesel fuel and heating oil, are removed from zone 1 by meansof line 5. A fraction boiling in the gas oil boiling range, about 450 F.to 700 F., is removed fromdistillation zone 1 by means of line 6 andpassed to a catalytic cracking zone 7. The cracking operation conductedin zone 7 may be any desired type employing a catalyst such as modifiednatural or synthetic clay or gel type catalysts, Examples of thesecatalysts are montmorillonite clays, silica-alumina, silica-magnesiacomposites and other conventional cracking catalysts. The process maycomprise Y Fractionator zone 8 is operated to remove relatively lowboiling constituents overhead by means of line 10'. Side streams ofintermediate boiling ranges are removed by means-of-lines-11 and--12. Abottoms product is segregated from fractionator 8 and removed throughline 14. If the cracking operation conducted in zone 7 is a fluid izedone, the product material 'withdrawn'throu'gh" line'l t -will contain asmall percentageof' catalystparticles'car- 'ried over from zone 7. Thus,it is necessary to :pass the product stream of line 14 to a settler 15or otherwise'to permit separation of the liquid hydrocarbonproduct'fromthe catalyst. A clarified hydrocarbon stream boil ing in-the rangeof about-650 F. to 1020 F, isremoved from zone 15 through line 16, andhandled as hereinafter described.

A bottoms fraction boiling above about 750 F.-, and up to about 1300 F.is removed from atmospheric crude pipe -'still l by means of 'line 20.This stream is introduced into vacuum crude pipe stil l'21 which isoperated at a bottoms temperature of about 700 F., and at a pressure ofabout 20 Hg. In' accordance with'conventionalprocedures, temperature andpressure conditions are-adjusted to segregate a lubricating oil fractionhaving a viscosity of about 40'to'45 S. S. U. at 2l0 F., and boiling inthe range from'about 700 to 900 F, by means of line'22. An intermediatefraction boiling in the lubricating oil boiling range and having aviscosity of about 48 to 55 S. S. U. at 210 F., and boiling in the rangefrom about 800 to l050 F. is segregated by means of line 23 while aheavier fraction having a viscosity in the range from about 80 to 100 S.S. U. at 210 F., and boiling in the range from'about 850 to 1150 F., isremoved by means of line 24. A heavier crude residuum fractioncomprising about 25% of the feed to zone 21 is segregated as a bottomsstream by means of line 25. This stream may be further refined asdesired.

In accordance with conventional procedures, portions of the respectiveside streams segregated by means of lines 22, 23 and 24 are combined asa wide distillate cut and passed to solvent treating zone 26 by means ofline 27. The balance of these side streams are'passed to catalyticcracking. The composition of the wide distillate made by combining thevarious side streams is adjusted to correspond to the market demands forthe various lube viscosity grades.

In solvent extraction zone 26 the Wide distillate fraction is contactedwith a solvent having a preferential selectivity for the relatively morearomatic type constituents as compared to the relatively more parafiinictype constituents. Solvents of this type are, for example, phenol,furfural, and the like. 'Usually from about A: to 4 volumes of solventare "utilized per volume of oil. The temperatures employed the zone 26are in the range from about 120 F. to 250 F. while pressures are in therange from about atmospheric to 50 lbs. per square inch. The solvent isintroduced into solvent contacting zone 26 by'meansof line 28. Thesolvent flows downwardly in zone 26 and countercurrently contacts theupflowing' oil under conditions wherein the more aromatic typeconstituents are dissolved in the solvent. A solvent extract phase isremoved from zone '26by means of line 29 and is processed to segregatethe solvent such as phenol from the aromatic typehydrocarbon-constituents. The solvent is recycled to'the'treating zone26.

A raffmate phase comprising the more'paraflinic type constituents andthe solvent suchas phenol is removed by means of line 30 and passed intoa solvent distillation zone 31 wherein temperature and pressureconditions are adjusted so as to "segregate the solvent from theparafllnic type constituents. The solvent is removed by means of line 32while the highly parafiinic oil phase is removed from zone 31 by meansof line 33. This phase is then passed to a dewaxing zone 34. In zone 34the oil is contacted with a suitable dewaxing solvent such as liquidpropane, methyl ethyl ketone,'mixed ketones, and the like. Zone 34comprises the necessary chilling and filtering stages forthe segregationof the dewaxing solvent,

"the Wax and the-oil and for-the recycling of the solvent to thedewaxing operation. A Wax phase is segregated from zone 34 by meansof'line 35 while the dewaxed oil also free of solvent is removed fromzone 34 by means of line 36. This dewaxed oil phase is usually passed toa vacuum pipe still operated at a pressure of about 20 mm; to 50mm.andat a bottoms temperature of about 650 F. to 700 F. The pressureconditions in zone 37 are adjusted to segregate a light lubricating oilfraction as, for example, one boiling in the range from about 700 F. to900 F., and having a viscosity Saybolt Universal of about 43 seconds at210 F. This low boiling fraction is removed from distillation zone 37 bymeans of line 38. An intermediate boiling lubricating oil fraction as,for example, one boiling in the range from about 800 F. to 1050 F., andhaving a viscosity Saybolt Universal of 56 seconds at 210 F., is removedfrom zone 37 by means of line 39. t A- high boiling fraction: such asone boiling in the 'rangefromabout 850 F. to'1l50 F, and

having a viscosity'of 150 seconds Saybolt Universal at 210 F. is removedfrom distillation zone 37 by means of line 40.

In accordancewith the present invention, the low boiling lubricating-oil'fr-action segregated from crude pipe still 21 by means of line 22 isnot blended with the intermediate and higher boiling virginconstituents, but is passed to catalytic cracking zone 7 by means ofline. In accordance with the present invention, the entire quantity ofheavy cycle oil is segregated in distillation zone 8 by means of line 16is not recycled to catalytic cracking zone 7; but at-1east-an amountequivalent to that diverted by means of line 41 is'blended with theintermediate and high boiling virgin constituents by means of line 42.The amount ofcycle oil soblen'ded will be such as to constitute fromabout 5% to about by volume of the blend.

By operating asde'scribed, that is, by substituting equivalent boiling'cycle'oil constituents for the low boiling virgin constituents, ahigher quality product is secured. Furthermore, a higher yield for thes'amefeed issecured upon solvent extraction. Still another advantage inthe extraction process is that the introduction of the catalytic cyclestock givesbetter phase separation in the contacting stages. He'nce,higher capacity can be run in the solvent extraction tower.

In order to further illustrate the'p'resent invention, the

following example is given:

EXAMPLE I Th're'e' solvent nearing" operations were conducted for themanufacture of high quality lubricating oils as follows:

Operation A.In this ope'ration the feed comprised a blend of viscosities(S. S. U. (Saybolt Seconds, Universal))- of 42, 51, and 81 210 F. Thesestreams were secured by a vacuum pipe still operation and were blendedas follows:

Vol. Vis.

percent S. S. U.

#1 Side Stream. 6. 8 42 #2 Side Stream 35. 2 51 #3 Side Stream- 58.0 St

ably higher yield of equivalent quality product with less phenol treat.

The results of the three operations are shown below:

Table I Operation A B Operating Conditions:

Temperature, Top F 204 204 204 Temperature, Bottom F 186 185 184 PhenolTreat Percent on Oil 238 228 153 Water in Phenol, Percent on Phenol. 3.3 3. 8 3. Water injected, Percent on PhenoL 3. 1 3. 4 4. Rail-mateYield,Vol. Percent on Oil Feed. 43. 3 47. 5 57. Phenol in Raffinate,Vol. Percent 17. 8 14. 0 15. Oil in Extract, Vol. Percent 19. 3 19. 619.

Dephenolized Raflinate: Feed Feed A B and O Gravity, API 60 F. 20.7 20.031.5 31. 5 30.0 Pour, F +105 +115 +120 +120 VisooStY 210 F 62. 8 63. 452. 1 52.3 53. 7 R. I. 75 C 1.4964 1.5019 1.4574 1. 4580 1.4621Dcphenolized Extract:

Gravity, API 60 F 13.8 10.9 8.4 R. I. 75 C 1.5261 1.5410 1.5535 DewaxedRatfinate:

Gravity, API 60 F 19. l 18. 5 30. 3 30. 7 29.1 R. I. 75 C 1. 5021 1.5060 1. 4689 1.4600 1. 4660 Pour, F 40 +45 +40 Viscosity 100 F 806 780824 309 349 Viscosty 210 F 68.3 67. 1 55. 2 58.8 55.8 Viscosity Index 5755 107% 129 106 From the above it is apparent that when substitutingcycie oil constituents for low boiling virgin constituents, a yield of47.5% is secured as compared to a yield of 43.3%. It is to be noted thatthe viscosity index of Oporation B is 129, as compared to 107 /2 ofOperation A. In Operation C, where conditions were adjusted to secureapproximately the same viscosity index, a yield of 57.1% was secured ascompared to a yield of 43.3%.

The dewaxed rafiinates from the respective operations were thendistilled into two corresponding viscosity fractions with the results asfollows:

Table II Operation A B C Viscosity Grade-SSU 210 F 43 56 43 v 56 43 66.Cut range on raflinate, Vol.

Percent 3-18 18-56 0-22 22-53 0-22 22-36 Finished Products Inspections:

Gravity, API 60 F 32.8 29.6 32. 6 28.6 Viscosity 100 F 151 407 155 407153 359 Viscosity 210 F 43. 9 59. 5 44. 5 59. 1 44.0 58.1 ViscosityIndex 114 103 118 105 112 98 Conradson Carbon, Wt.

Percent .05 .05 0.0 .02 Sligh N 0., mg. sludge/10 gms. of oil in 24hours. 26 1.8 9. 7 1.4 4.9 0.5

It is apparent from the above that when cracked cycle constituents aresubstituted for low boiling virgin constituents, the oxidation stabilitycharacteristics are improved. This is shown by the Sligh value of 26 onthe 43 viscosity grade as compared to values of 5 to 10 secured inOperations B and C. It is to be noted that Operations B and C also gavelower Conradson carbon values, thus indicating superior engineperformance.

In the current operations the feed stock blend containing cycle oilconstituents settled in about 2 /2 minutes to clear phases, as comparedto 3 /2 minutes when the oil feed blend comprised entirely virgindistillates. This indicates substantially increased throughputs forcommercial plants processing blends whose lower boiling constituentscomprise cracked constituents.

What is claimed is:

1. A process for producing lubricating oil by solvent extraction of avirgin lubricating oil distillate normally boiling in the range of about700 to 1150 R, which comprises: segregating a higher boiling fraction ofsaid distillate boiling in the range of about 800 to 1150 F., therebyexcluding the lowest boiling fraction from said distillate, blendingwith said higher boiling fraction a catalytic cycle oil constitutingcatalytically cracked constituents boiling in the range of about 650 to1020 F., in an amount such that said catalytic cycle oil will constitutefrom about 5% to about 40% of the volume of the blend, and thereaftertreating said blend with a solvent having a preferential selectivity foraromatic type constituents, and segregating a raflinate product.

2. The process defined by claim 1 in which the said solvent is selectedfrom the group consisting of phenol and furfural.

3. The process defined by claim 1 in which the said solvent is phenol.

4. The process defined by claim 1 whereinthe said catalytic cycle oilhas substantially the same viscosityas the said excluded lowest boilingfraction of the said virgin lubricating oil distillate.

5. The process defined by claim 1 wherein the quantity of said catalyticcycle oil in said blend is substantially the same as the quantity of thesaid excluded lowest boiling I fraction of the said virgin lubricatingoil distillate.

1 References Cited in the file of this patent UNITED STATES PATENTS

1. A PROCESS FOR PRODUCING LUBRICATING OIL BY SOLVENT EXTRACTION OF AVIRGIN LUBRICATING OIL DISTILLATE NORMALLY BOILING IN THE RANGE OF ABOUT700* TO 1150* F., WHICH COMPRISES: SEGREGATING A HIGHER BOILING FRACTIONOF SAID DISTILLATE BOILING IN THE RANGE OF ABOUT 800* TO 1150* F.,THEREBY EXCLUDING THE LOWEST BOILING FRACTION FROM SAID DISTILLATE,BLENDING WITH SAID HIGHER BOILING FRACTION A CATALYTIC CYCLE OILCONSTITUTING CATALYTICALLY CRACKED CON-